As a material of a conductive component for electric and electronic device, a Cu—Zn alloy is widely used in the related art from the viewpoint of, for example, balance between strength, workability, and cost.
In addition, in the case of a terminal such as a connector, in order to improve reliability of contact with an opposite-side conductive member, a surface of a substrate (blank) formed of a Cu—Zn alloy is plated with tin (Sn). In a conductive component such as a connector obtained by plating a surface of a Cu—Zn alloy as a substrate with Sn, a Cu—Zn—Sn-based alloy may be used in order to improve the recycling efficiency of the Sn-plated substrate and the strength.
Here, typically, a conductive component for electric and electronic device such as a connector is manufactured by punching a sheet (rolled sheet) having a thickness of about 0.05 mm to 1.0 mm into a predetermined shape and bending at least a portion of the sheet. In this case, a peripheral portion around the bent portion is brought into contact with an opposite-side conductive member so as to obtain an electric connection with the opposite-side conductive member, and due to the spring properties of the bent portion, the contact state with the opposite-side conductive member is maintained.
It is preferable that a copper alloy for electric and electronic device used for a conductive component for electric and electronic device is superior in conductivity, rollability, and punchability. Further, as described above, in the case of the connector or the like in which the contact state between the peripheral portion around the bent portion and the opposite-side conductive member is maintained due to the spring properties of the bent portion obtained by bending, bendability and stress relaxation resistance are required to be superior.
For example, Patent Documents 1 to 3 disclose methods for improving the stress relaxation resistance of a Cu—Zn—Sn-based alloy.
Patent Document 1 describes that stress relaxation resistance can be improved by adding Ni to a Cu—Zn—Sn-based alloy to produce a Ni—P compound. In addition, Patent Document 1 describes that the addition of Fe is also efficient for improvement of stress relaxation resistance.
Patent Document 2 describes that strength, elasticity, and heat resistance can be improved by adding Ni and Fe to a Cu—Zn—Sn-based alloy together with P to produce a compound. The above-described improvement of strength, elasticity, and heat resistance implies improvement of stress relaxation resistance.
In addition, Patent Document 3 describes that stress relaxation resistance can be improved by adding Ni to a Cu—Zn—Sn-based alloy and adjusting a Ni/Sn ratio to be in a specific range. In addition, Patent Document 3 describes that the addition of a small amount of Fe is also efficient for improving stress relaxation resistance.
Further, Patent Document 4 targeted for a lead frame material describes that stress relaxation resistance can be improved by adding Ni and Fe to a Cu—Zn—Sn-based alloy together with P, adjusting an atomic ratio (Fe+Ni)/P to be in a range of 0.2 to 3, and producing a Fe—P-based compound, a Ni—P-based compound, and a Fe—Ni—P-based compound.